The calls for Tiger Woods to get help did not go unheeded. On Jan. 16, after weeks of sordid allegations regarding the star golfer's extramarital affairs, RadarOnline.com reported that Woods had enrolled in the Gentle Path program at Pine Grove Behavioral Health and Addiction Services, in Hattiesburg, Miss., to be treated for sex addiction. Local television stations later confirmed the story. (See the top 10 apologies.)

Few people know what actually happens at sex rehab. While those who treat it say sex addiction is a disease like any other compulsion, the field is in its infancy: there is virtually no research on it, compared with the vast resources on drug or alcohol addiction. "You look at ways that your behavior has made your life unmanageable. That's really the question," says Benoit Denizet-Lewis, author of America Anonymous: Eight Addicts in Search of a Life, who has been treated for sex addiction himself. "That often differentiates a sex addict from a non-sex addict."

Sex addiction is marked not simply by poor decision-making in the face of temptation, but also by a sense of powerlessness before one's own compulsive behavior. There are many types of sex addicts, including so-called sexual anorexics who avoid physical intimacy with their partner and seek it out in fantasies or with others. Despite the shortage of statistics, researchers agree that the vast majority of sex addicts  over 90%  are men. Rob Weiss, founder and executive director of the Sexual Recovery Institute in Southern California, estimates that up to 5% of Americans deal with some form of sex addiction, though he says there is no real way to know. (See more about Tiger Woods.)

Rehab length varies from two-week outpatient seminars to inpatient clinics that keep patients for up to six weeks, like the one where Woods is staying. Treatment  to address both the addiction and its underlying causes  involves a mix of one-on-one sessions, group therapy and family counseling, with addicts and their partners encouraged to participate in supplemental 12-step programs.

The first step in treatment of sexual addiction is a full evaluation of a patient's history and any past trauma. "All the men I've worked with  and I've worked with thousands of them over the years  have some profound experience of abuse and/or neglect in childhood," says Weiss. Without addressing the underlying sexual, physical or emotional trauma that usually leads to addiction, there is little hope of ending it.

The second stage of treatment involves confronting patients' distorted view of reality. Did the addict really believe that paying for a sensual massage was not the same thing as hiring a prostitute? Or that he or she could spend most of the day surfing the Internet for pornography and that no one would find out? These questions are not meant to shame a patient, but to force him or her to understand what really happened. As Weiss puts it, "We may not stop the behavior, but we're going to ruin it for you." (See TIME's sex covers.)

The last stage of treatment is relapse prevention. Therapists and patients discuss triggers for addictive behavior  unstructured time alone, for example  and identify ways to avoid them. Brian McGinness, a senior cost estimator at a Michigan commercial construction manufacturer, spent the first nine years of his marriage addicted to pornography. His treatment was supervised by members of his church who belonged to an anti-pornography ministry group called XXXchurch and a neighborhood friend, who all acted as "accountability partners," monitoring his Internet usage after he decided to get sober. (Sex addiction shares use of the word sobriety with other forms of addiction, though the definition varies on the basis of an individually determined level of acceptable sexual behavior.) With the monitors' help, which he no longer needs on a regular basis, McGinness has not looked at pornography for the past four years. (See the top 10 medical breakthroughs of 2009.)

A patient's partner can also play an integral role in his or her treatment. Woods' wife Elin Nordegren has already visited him at Pine Grove. "Recovery is a three-legged stool for a couple  his recovery, her recovery and healing, and then the marriage recovery," says Dr. Douglas Weiss (no relation to Rob Weiss), executive director of the Heart to Heart Counseling Center in Colorado, who describes himself as being sober from his own sex addiction for more than 20 years. Addicts are encouraged to disclose the full range of their behavior to their partner when confronting their distortions of reality in the second stage of treatment. If an addict happens to contract an STD and never tells his wife, "his behavior could kill her," Weiss notes.

Although Woods may be in a six-week program, his therapy is likely to be ongoing. Indeed, at Heart to Heart, clients are encouraged to come back for annual polygraphs to test their sobriety. According to Maureen Canning, a clinical consultant at Meadows Addiction Treatment Center in Arizona, simply working through the addiction could take two to five years of therapy, enhanced by 12-step programs for both partners; working through related trauma could take a lifetime. "Sex addiction is not about remaining abstinent for the rest of your life," says Denizet-Lewis. "It is about learning to have sex in a way that makes you happy again."